I've never used Chromium Oxide powder before, but I do have experience with the Hand American Liquid. I believe that you can mix the powder with a wet ingredient (mineral oil?) to form a slurry that you could apply to leather. When I use my Chromium Oxide Liquid, I just apply it to a clean page of a notebook with a piece of cloth or sponge. Then I strop and just throw the used notebook page away. I'm sure someone will correct me if I've lead you astray, but hopefully this will get you started.